1. Field of the Invention
The invention relates generally to a hydromechanical drive unit for a vehicle and more particularly to a hydromechanical drive unit which is designed to be located between two driven vehicle axles and which includes a swash-plate type hydrostatic axial piston engine and a coaxial downstream mechanical transmission with an output shaft having a distal end for connection with an axle of the vehicle.
2. Description of Related Prior Art
This type of drive unit is used, for example, in construction vehicles, such as loaders and excavators to obtain a speed conversion range which will permit the operation of the vehicle at a construction site and over the road. To accomplish this result, a shiftable mechanical transmission is located downstream from the axial piston engine. A spur transmission having an input shaft connected to the shaft of the axial piston engine is generally used. The output shaft of the spur transmission is the output shaft of the hydromechanical drive unit and is located parallel to the input shaft. The drive unit is centrally located to enable the ends of the output shaft to be connected to intermediate shafts which generally function as universal shafts and are connected to the differential of a vehicle axle. These prior art hydromechanical drive units require a large number of component parts which result in high manufacturing and assembly costs. Furthermore, the use of parallel shafts results in a drive unit having large dimensions.